Apparatus and method for single substrate processing

ABSTRACT

In a method for treating a semiconductor substrate, a single substrate is positioned in a single-substrate process chamber and subjected to wet etching, cleaning and/or drying steps. The single substrate may be exposed to etch or clean chemistry in the single-substrate processing chamber as turbulence is induced in the etch or clean chemistry to thin the boundary layer of fluid attached to the substrate. Megasonic energy and/or disturbances in the chamber surfaces may provide the turbulence for boundary layer thinning. According to another aspect of a method according to the present invention, megasonic energy may be directed into a region within the single-substrate process chamber to create a zone of boundary layer thinning across the substrate surface, and a single substrate may be translated through the zone during a rinsing or cleaning process within the chamber to optimize cleaning/rinsing performance within the zone.

FIELD OF THE INVENTION

[0001] The present invention relates to the field of surface preparationsystems and methods for semiconductor substrates and the like.

BACKGROUND OF THE INVENTION

[0002] In certain industries there are processes that must be used tobring objects to an extraordinarily high level of cleanliness. Forexample, in the fabrication of semiconductor substrates, multiplecleaning steps are typically required to remove impurities from thesurfaces of the substrates before subsequent processing. The cleaning ofa substrate, known as surface preparation, has for years been performedby collecting multiple substrates into a batch and subjecting the batchto a sequence of chemical and rinse steps and eventually to a finaldrying step. A typical surface preparation procedure may include etch,clean, rinse and dry steps. An etch step may involve immersing thesubstrates in an etch solution of HF to remove surface oxidation andmetallic impurities and then thoroughly rinsing the substrates in highpurity deionized water (DI) to remove etch chemicals from thesubstrates. During a typical cleaning step, the substrates are exposedto a cleaning solution that may include water, ammonia or hydrochloricacid, and hydrogen peroxide. After cleaning, the substrates are rinsedusing ultra-pure water and then dried using one of several known dryingprocesses.

[0003] Currently, there are several types of tools and methods used inindustry to carry out the surface preparation process. The tool mostprevalent in conventional cleaning applications is the immersion wetcleaning platform, or “wet bench.” In wet bench processing, a batch ofsubstrates is typically arranged on a substrate-carrying cassette. Thecassette is dipped into a series of process vessels, where certainvessels contain chemicals needed for clean or etch functions, whileothers contain deionized water (“DI”) for the rinsing of these chemicalsfrom the substrate surfaces. The cleaning vessels may be provided withpiezoelectric transducers that propagate megasonic energy into thecleaning solution. The megasonic energy enhances cleaning by inducingmicrocavitation in the cleaning solution, which helps to dislodgeparticles off of the substrate surfaces. After the substrates are etchedand/or cleaned and then rinsed, they are dried. Often drying isfacilitated using a solvent such as isopropyl alcohol (IPA), whichreduces the surface tension of water attached to the substrate surface.

[0004] Another type of surface preparation tool and method utilized inthe semiconductor industry is one in which a number of surfacepreparation steps (e.g. clean, etch, rinse and/or dry) may be performedon a batch of substrates within a single vessel. Tools of this type caneliminate substrate-transfer steps previously required by wet benchtechnology, and have thus gained acceptance in the industry due to theirreduced risk of breakage, particle contamination and their reduction infootprint size.

[0005] Further desirable, however, is a chamber and method in whichmultiple surface preparation steps can be performed on a singlesubstrate (e.g. a 200 mm, 300 mm or 450 mm diameter substrate), asopposed to a batch of substrates. It is thus an object of the presentinvention to provide a chamber and method for performing one or moresurface preparation steps on a single substrate.

SUMMARY OF THE INVENTION

[0006] In one aspect of the present invention, a single substrate ispositioned in a single-substrate process chamber and subjected to wetetching, cleaning and/or drying steps. According to another aspect ofthe present invention, a single substrate is exposed to etch or cleanchemistry in the single-substrate processing chamber as boundary layerthinning is induced in the region of the substrate. According to yetanother aspect of a method according to the present invention, boundarylayer thinning is induced in a zone within the single-substrate processchamber, and a single substrate is translated through the zone during aprocess within the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1A is a schematic illustration of a single substrateprocessing chamber, showing the substrate positioned in the lowerinterior region of the chamber.

[0008]FIG. 1B is a schematic illustration of a single substrateprocessing chamber, showing the substrate positioned in the upperinterior region of the chamber.

[0009]FIG. 1C is a block diagram illustrating one example of a fluidhandling system useable with the chamber of FIG. 1A.

[0010]FIG. 1D is a block diagram illustrating a second example of afluid handling system useable with the chamber of FIG. 1A.

[0011]FIGS. 2A-2C are a sequence of cross-section views of the chamberinterior, illustrating movement of the substrate between the upperinterior region and the lower interior region.

[0012]FIG. 3A is a cross-sectional perspective view of a secondembodiment of a single substrate processing chamber showing the fluidmanifold in the closed position. The figure also shows automationprovided for transporting a substrate into, out of, and within thechamber.

[0013]FIG. 3B is a cross-sectional perspective view of the singlesubstrate processing chamber of FIG. 3A showing the fluid manifold inthe opened position. The transport automation shown in FIG. 3A is notshown in FIG. 3B.

[0014]FIG. 4 is a cross-sectional perspective view of the upper manifoldand a portion of the tank of the second embodiment of FIG. 3A.

[0015]FIG. 5 is a cross-sectional side view of the second embodiment ofFIG. 3A.

[0016]FIG. 6 is a perspective view of an end effector of the secondembodiment of FIG. 3A. The end effector is shown carrying a substrate.

[0017]FIG. 7A is a perspective view of one prong of a second embodimentof an end effector during transport of a substrate.

[0018]FIG. 7B is a perspective view showing the end effector of FIG. 7Aduring transport of a substrate into or out of the chamber.

[0019]FIG. 7C is a perspective view showing the end effector, substrateand chamber during transport of the substrate into or out of thechamber, with the substrate beginning to make contact with the bottomnotch of the chamber.

[0020]FIG. 7D is a perspective view showing the end effector, substrateand chamber during processing of the substrate within the chamber.

[0021]FIG. 7E is a perspective view similar to the view of FIG. 7Ashowing one prong of the end effector during processing of the substratewithin the chamber.

[0022]FIG. 8 is a cross-section view of a chamber according to a thirdembodiment.

DETAILED DESCRIPTION

[0023] Three embodiments of single substrate chambers and associatedprocesses are described herein. Each of the described chambers/methodsperforms wet processing steps such as (but not limited to) etching,cleaning, rinsing and/or drying on a single substrate (such as, forexample a semi-conductor wafer substrate) using a single chamber. Aswill be appreciated from the description that follows, such chambers andmethods are beneficial in that each substrate treated using thechamber/method is exposed to the same process conditions to which theother substrates undergoing the same process are exposed. This yieldshigher precision processing than seen in a batch system, in which asubstrate positioned in one part of a substrate batch may be exposed toslightly different process conditions (such as fluid flow conditions,chemical concentrations, temperatures etc.) than a substrate positionedin a different part of the batch. For example, a substrate at the end ofa longitudinal array of substrates may see different conditions than asubstrate at the center of the same array. Such variations in conditionscan yield batches lacking in uniformity between substrates.

[0024] Single substrate chambers/methods such as those described hereinare further beneficial in that each substrate is exposed to processfluids for a shorter amount of time than is required in batchprocessing. Moreover, for applications where only a few substrates needprocessing (e.g. in a prototype engineering context), the individualsrequiring the processed substrates need only wait a few minutes toreceive the treated substrates, rather than waiting a full hour or morefor the substrates to be processed in a batch-type chamber. Moreover,the chambers/methods described herein can be practiced using the same orsmaller volumes of process fluids (on a substrate-per-substrate basis)than would be used in corresponding batch processes.

[0025] First Embodiment—Structure

[0026] Features of a first embodiment of a single substrate processingchamber are schematically shown in FIGS. 1A-1D. Referring to FIG. 1A, afirst embodiment 2 of a single substrate processing chamber includes achamber 10 having sidewalls 11 defining a lower interior region 12 aproportioned to receive a substrate S for processing, an upper interiorregion 12 b, and an opening 14 in the upper interior region 12 a.

[0027] The first embodiment includes a substrate transport device 28.Transport device includes an end effector 30 configured to engage asubstrate S, and is driven by conventional automation (not shown) tomove the substrate S through opening 14 into and out of the chamber 10in an edgewise direction. Transport device 28 is further configured tocause end effector 30 to move the substrate between the lower interiorregion 12 a and the upper interior region 12 b, as described below inconnection with operation of the device.

[0028] Transport device 28 may also carry a lid 29 that closes againstopening 14 when the end effector 30 is lowered. The lid 29 may remain inplace, even as the end effector moves the substrate between regions 12a, 12 b during processing, and be later withdrawn so that the endeffector 30 can remove substrate S from the chamber.

[0029] The upper end of the lower interior region 12 a may be narrowedto include a throat section to increase the velocity of fluid flowingthrough the throat section from the lower section of the chamber. Thebottom of the chamber 10 may be flat or contoured to conform to theshape of the lower edge of the substrate.

[0030] Fluid Handling System

[0031] The first embodiment 2 is preferably provided with a fluidhandling system 26 configured to carry various process fluids (e.g. etchfluids, cleaning fluids, rinse water etc.) into the lower interiorregion 12 b of chamber 10.

[0032] There are various ways in which the fluid handling system 26 canbe configured. For example, as shown in FIGS. 1A and 1B, a window 16 maybe formed in the lower interior region 12 b and one or more manifoldsmay be moveable into place at the window 16 to direct process fluidsinto the chamber 10. The manifolds and the window 16 are preferablysealed within a containment vessel 26, a sealed housing that exhaustsfumes, gases etc. that may be released from the manifolds so as toprevent their escape into the surrounding environment.

[0033] A fluid manifold 18 is positionable to direct process fluids(e.g. chemistries for etching, and DI water for rinsing) into the lowerinterior 12 a of chamber 10 via window 16. Fluid manifold 18 includes atleast one, but preferably multiple, openings 20 through which fluid isdirected into the chamber 10. The fluid manifold 18 is moveable betweena closed position (FIG. 1A) in which the manifold is oriented to directfluids into the window 16 via openings 20, and an open position (FIG.1B) in which the openings 20 are positioned away from the window 16. Thefluid manifold 18 may be moveable between the closed and open positionsusing standard automation. Fluid manifold 18 may optionally include amegasonic transducer (not shown) having one or more transducers fordirecting megasonic energy into fluids in the chamber as will bedescribed in greater detail below. For simplicity, the term “megasonictransducer” will be used herein to encompass transducer assembliescomprised of a single transducer or an array of multiple transducers.

[0034] A second fluid manifold, which will be referred to as themegasonics manifold 22, is provided and includes one or more inlets 24.Like the fluid manifold 18, the megasonics manifold 22 is moveablebetween a closed position (FIG. 1B) in which the inlets 24 are orientedto direct fluid (e.g. cleaning solutions and DI water for rinsing) fromthe megasonics manifold 22 through window 16, and an opened position(FIG. 1A) in which the inlets 24 are spaced from the window 16,permitting the manifold 18 to be brought into its closed position. Themegasonics manifold 22 may be moveable between the closed and openpositions.

[0035] The megasonics manifold 22 includes a megasonic transducer, whichmay include a single transducer or an array of multiple transducers,oriented to direct megasonic energy into the chamber interior via thewindow. When the me gasonic transducer(s) direct megasonic energy intofluid in the chamber, they induce acoustic streaming within thefluid—i.e. streams of microbubbles that aid in removal of contaminantsfrom the substrate and that keep particles in motion within the, processfluid so as to avoid their reattachment to the substrate.

[0036] Referring to the block diagram of FIG. 1C, the fluid handlingsystem 26 may include a system of valves and conduits for directingfluids into the manifolds 18, 22. A DI water source and a source of etchfluid are fluidly coupled to manifold 18, and valves 19 a, 19 b governflow of these fluids into the manifold 1.8. It should be appreciatedthat while the etch plumbing is shown configured for injection into a DIwater stream, etch fluid may alternatively be independently directedinto the manifold 18. Similarly, valves 23 a, 23 b and associatedconduits couple sources of DI water and cleaning fluid to megasonicsmanifold 22.

[0037] The configuration of the fluid handling system shown in FIG. 1Cprovides two means for evacuation of fluid from the chamber 10. First,dedicated sealed containers 31 a, 31 b are provided for rapidlywithdrawing fluids from the chamber. Preferably, each sealed containeris dedicated to a particular type of process fluid, e.g. an etch fluidor a cleaning fluid, so as to prevent cross-contamination of processfluids.

[0038] Each container 31 a, 31 b is coupled to the chamber 10 by valves27 a, 27 b and associated drain plumbing 29 a, 29 b. Alternatively, thevalves and drain plumbing may couple the sealed containers 31 a, 31 b tothe manifolds 18, 22 (not shown). The sealed containers 31 a, 31 b aremaintained at negative pressure and the valves 27 a, 27 b are keptclosed except when they are opened for evacuation of the chamber. At theend of the etch process, the valve 27 a may be opened, causing rapidremoval of the etch fluid into the negative pressure container 31 a forsubsequent re-use. This rapid removal of the fluid helps to shear etchsolution from the substrate surface. It also optimizes uniformity acrossthe substrate surface by creating a sharp transition between exposure ofthe substrate to the etch solution and separation of the substrate fromthe bulk etch solution—thus minimizing surface variations between thetop portion of the substrate and the lower portion of the substrate.This transition may be sharpened further, and the shearing of the etchsolution from the substrate may be enhanced, by using the end effectorto pull the substrate into the upper interior region 12 b during therapid fluid removal.

[0039] The second evacuation means provided in the embodiment of FIG. 1Cutilizes the megasonics manifolds 18, 22, which are moved to the openedposition to dump fluid from the chamber into a drain (not shown).

[0040] As another example of a fluid distribution system, a fluidmanifold 23 as shown in the block diagram of FIG. 1D may be providedwith multiple dedicated valves 33 a, 33 b, and 33 c feeding processfluids into the manifold 23. In such a configuration, one valve may feedetch solution into the manifold, whereas another may feed cleaningsolution and another may feed rinse water. This type of dedicatedconfiguration is desirable in that it minimizes the number of commonplumbing components (i.e. those that are exposed to multiple processchemicals) and thus minimizes the amount of rinsing required for theplumbing between process steps.

[0041] In this example, manifold 23 may include a megasonic transducer,or a megasonic transducer may be positioned in a lower region of thechamber 10. The manifold 23 may be fixed or moveable to an openedposition for a rapid evacuation of the chamber 10. Sealed negativepressure containers 31 a, 31 b may also provide an additional means ofevacuation as described with respect to the FIG. 1C embodiment. Thesealed containers 31 a, 31 b may be coupled to the manifold itself, orto the chamber 10 as shown in FIG. 1D.

[0042] Upper Megasonics

[0043] Referring again to FIGS. 1A and 1B, an overflow weir 34 is formedalong the chamber periphery at the top of the lower interior region 12a. Process fluid flowing into the chamber from manifolds 18, 22 cascadesinto the weir 34 and into overflow plumbing 35 for recirculation ordisposal. A pair of megasonic transducers 32 a, 32 b, each of which mayinclude a single transducer or an array of multiple transducers, arepositioned at an elevation below that of the weir 34, and are orientedto direct megasonic energy into an upper portion of lower interiorregion 12 a of the chamber 10. Transducer 32 a directs megasonic energytowards the front surface of a substrate, while transducer 32 b directsmegasonic energy towards the rear surface of the substrate.

[0044] The transducers are preferably positioned such that the energybeam interacts with the substrate surface at or just below thegas/liquid interface, e.g. at a level within the top 0-20% of the liquidin the lower interior 12 a. The transducers may be configured to directmegasonic energy in a direction normal to the substrate surface or at anangle from normal. Preferably, energy is directed at an angle ofapproximately 0-30 degrees from normal, and most preferablyapproximately 5-30 degrees from normal. Directing the megasonic energyfrom transducers 32 a,b at an angle from normal to the substrate surfacecan have several advantages. For example, directing the energy towardsthe substrate at an angle minimizes interference between the emittedenergy and return waves of energy reflected off the substrate surface,thus allowing power transfer to the solution to be maximized. It alsoallows greater control over the power delivered to the solution. It hasbeen found that when the transducers are parallel to the substratesurface, the power delivered to the solution is highly sensitive tovariations in the distance between the substrate surface and thetransducer. Angling the transducers reduces this sensitivity and thusallows the power level to be tuned more accurately. The angledtransducers are further beneficial in that their energy tends to breakup the meniscus of fluid extending between the substrate and the bulkfluid (particularly when the substrate is drawn upwardly through theband of energy emitted by the transducers) thus preventing particlemovement towards the substrate surface.

[0045] Additionally, directing megasonic energy at an angle to thesubstrate surface creates a velocity vector towards overflow weir 34,which helps to move particles away from the substrate and into the weir.For substrates having fine features, however, the angle at which theenergy propagates towards the substrate front surface must be selectedso as to minimize the chance that side forces imparted by the megasonicenergy will damage fine structures.

[0046] It may be desirable to provide the transducers 32 a, 32 b to beindependently adjustable in terms of angle relative to normal and/orpower. For example, if angled megasonic energy is directed by transducer32 a towards the substrate front surface, it may be desirable to havethe energy from transducer 32 b propagate towards the back surface at adirection normal to the substrate surface. Doing so can prevent breakageof features on the front surface by countering the forces impartedagainst the front surface by the angled energy. Moreover, while arelatively lower power or no power may be desirable against thesubstrate front surface so as to avoid damage to fine features, a higherpower may be transmitted against the back surface (at an angle or in adirection normal to the substrate). The higher power can resonatethrough the substrate and enhance microcavitation in the trenches on thesubstrate front—thereby helping to flush impurities from the trenchcavities.

[0047] Additionally, providing the transducers 32 a, 32 b to have anadjustable angle permits the angle to be changed depending on the natureof the substrate (e.g. fine features) and also depending on the processstep being carried out. For example, it may be desirable to have one orboth of the transducers 32 a, 32 b propagate energy at an angle to thesubstrate during the cleaning step, and then normal to the substratesurface during the drying step (see below). In some instances it mayalso be desirable to have a single transducer, or more than twotransducers, rather than the pair of transducers 32 a, 32 b.

[0048] Vapor inlet ports 36, fluid applicators 37, and gas manifold 38extend into upper interior region 12 b of the chamber 10. Each isfluidly coupled to a system of conduits that deliver the appropriatevapors and gases to the ports as needed during processing. The fluidapplicators 37 are preferably configured to inject a stream or streamsof process fluid into the upper interior region 12 b. It is preferablethat the stream(s) of injected fluid collectively extend for a width atleast as wide as the diameter of the substrate, such that fluid may beuniformly applied at high velocity across the width of the substrate asthe substrate is moved past the stream(s). To this end, the fluidapplicators may comprise a pair of narrow elongate slots in the wall ofthe upper region 12 b of the chamber. It is also preferable that thefluid applicators 37 are spaced from the substrate by a very closedistance.

[0049] First Embodiment—Operation

[0050] The system 2 may be used for various processes, including thoserequiring one or more of the steps of wet etching, cleaning, rinsing anddrying. Its use will be described in the context of an etch, clean anddrying process, in which rinses are performed following etching andcleaning. Performance of this combination of steps is efficient in thatit allows multiple steps to be performed in a single chamber, and itminimizes post-treatment particle reattachment since substrates leavethe chamber dry. Moreover, performance of the multiple steps in a singlechamber minimizes buildup of particles and residue in the processchamber, since each time a substrate goes through the sequence ofprocesses, the chamber itself is cleaned and dried. Naturally, variousother combinations of these or other process steps may be performedwithout departing from the scope of the present invention.

[0051] Etching

[0052] If processing is to begin with an etch procedure, operation ofthe first embodiment begins with fluid manifold 18 in the closedposition as shown in FIG. 1A. The lower portion 12 a of the chamber 10is filled with process fluids necessary for the etching procedure (forexample, hydrofluoric acid (HF), ammonium fluoride and HF, or bufferedoxide). These fluids may be injected into a DI water stream enteringfluid manifold 18 (using, for example, the fluid handling configurationshown in FIG. 1C), causing them to flow into the chamber 10 with the DIwater. Alternatively, the etch solution may flow directly into manifold18 and into chamber, or, if the fluid handling configuration of FIG. 1Dis used, the solution may enter manifold 23 and chamber 10 via dedicatedvalve 33 b. In either case, the solution cascading over weir 34 may berecirculated back into the chamber 10 throughout the etch process, suchas by collecting it into a (preferably) temperature-controlled vesseland circulating it back to manifold 18 for re-introduction into thechamber 10. Alternatively, the etch process may be a “one-pass” processin which the overflowing etch solution is directed to a drain fordisposal. As a third alternative, the flow of etch solution may beterminated once the lower portion 12 a of the chamber has been filled.

[0053] Substrate S is engaged by end effector 30 and moved into the etchsolution by the substrate transport device 28. Substrate S is positionedin the lower portion 12 a of the chamber, i.e. at an elevation belowthat of the weir 34, so that the substrate is fully immersed in the etchsolution.

[0054] In wet processing, a relatively stagnant fluid layer known as a“boundary layer” is typically present at the substrate surface. A thickboundary layer can inhibit the ability of an etch or cleaning solutionto reach and react with the substances that are to be removed from thesubstrate surface. It is thus desirable to minimize the thickness of theboundary layer of fluid attached to the substrate surface so that theetch chemicals can more effectively contact the substrate surface.Boundary layer thinning may be accomplished by inducing turbulence inthe etch fluid using disturbances formed into the sidewalls of thechamber. For example, a random or patterned topography may be machinedinto the side walls so that fluid flowing through the chamber 10 fromthe manifold is turbulent rather than laminar. Turbulence may be furtherincreased by using relatively high fluid flow rates and temperatures. Asanother alternative, additional inlet ports (not shown) may be formedinto the side walls and process fluids may enter the chamber via theseports as well as via manifold 18 so as to cause disruptions in the flowfrom the manifold 18. As yet another alternative, a megasonic transducerof a type that could withstand the etch fluids (e.g. sapphire,fluoroplastic, PFA, Halar, ECTFE, coated metal, orpolytetrafluoroethylene (PTFE) sold under the trade name Teflon) couldbe positioned in the chamber 10 to cause turbulent flow of the etchfluid and to thus induce or contribute to boundary layer thinning.

[0055] Post-Etch Quench and Rinse

[0056] At the end of the etch procedure, flow of etch solution isterminated and a post-etch rinsing step may be carried out to removeetch solution from the substrate and chamber. The post-etch rinsing stepmay be initiated in one of several ways. In one example, manifold 18 ismoved to the opened position (FIG. 1B), draining the etch solution fromthe chamber 10 into a drain (not shown), from which it is directed forcollection/disposal. The manifold is then closed and DI rinse water isintroduced into the chamber via fluid manifold 18 and caused to cascadethrough the chamber and over weir 34. Alternatively, the step of openingthe manifold 18 may be eliminated, in which case flow of DI water ispermitted to continue until the etch solution is thoroughly rinsed fromthe substrate, manifold and chamber.

[0057] As another alternative, the etch fluid may be rapidly removedfrom chamber 10 by opening valve 27 a (FIG. 1C), causing the fluid to besuctioned into sealed negative pressure container 31 a for later re-useor disposal. As discussed in the “Structure” section above, this type ofrapid removal of etch solution minimizes etch variations across thesubstrate surface by more sharply ending the exposure of the substrateto the bulk etch fluid. This process is preferably enhanced bysimultaneously using the end effector 30 to withdraw the substrate fromthe chamber lower portion 12 a into the upper portion 12 b. Withdrawalmay be carried at any desired speed, although a rate of 25-300 mm/sechas been found beneficial.

[0058] The post-etch rinse process may preferably include a boundarylayer thinning process to accelerate diffusion of the etch chemistryfrom the surface of the substrate out of the boundary layer of fluidattached to the substrate and into the surrounding bulk fluid. Thisdiffusion process is known in the art as “quenching” and is instrumentalin terminating etching of the substrate surface. A megasonic transducerpositioned at or near the chamber bottom (e.g. a transducer provided aspart of fluid manifold 18, or a transducer mounted separately within thechamber, or the transducer of megasonics manifold 22) may also beutilized for this purpose.

[0059] The accelerated quench is preferably performed in combinationwith the rapid removal of the bulk etch fluid (e.g. in approximatelyless than 1.0 second), such as by suction of the fluid into the negativepressure container 31 a (FIG. 1C) and the simultaneous withdrawal of thesubstrate into the upper portion 12 b of the chamber. However, any ofthe evacuation processes described above, such as opening of themanifold 18, may also be used preferably in combination with the liftingof the substrate from the chamber 10.

[0060] Next, the chamber 10 is rapidly filled with a quenchant such asDI water. Since at this time the substrate is in the upper portion 12 bof the chamber, rapid filling can be performed without concern that thesubstrate will be splashed—an occurrence which could lead to lack ofuniformity across the substrate's surface. As the chamber 10 begins tofill, the megasonic transducer in the chamber bottom (i.e. depending onthe fluid handling system, this may be the transducer of manifold 22,manifold 18, or a lower chamber transducer) is operated at low power.The megasonic power is increased as the chamber fills with DI water.Once the lower portion 12 a of the chamber has been partially filled,the substrate is lowered into the quenchant. The turbulence created bythe megasonic energy facilitates boundary layer thinning that thusfacilitates diffusion of etch chemistry from the boundary layer into thebulk rinse water.

[0061] The megasonic power is increased as the volume of quenchant inthe chamber increases. Beginning at a lower power and increasing thepower as the chamber fills minimizes the chance of high power megasonicenergy causing splashing of quenchant onto the substrate, and alsominimizes the likelihood that residual etch solution on the substrateand in the tank would aggressively etch the bottom portion of thesubstrate immersed in the water.

[0062] The flow of DI water or other quenchant into the chamberpreferably continues even after the substrate is fully immersed. Theupper megasonic transducers 32 a, 32 b are energized. These transducersimpart megasonic energy into an adjacent region of the DI water. Theenergy creates a zone Z. (FIGS. 2A through 2C) in which the turbulencecreated by the megasonic energy causes boundary layer thinning and thusfacilitates gettering of the etch material away from the substrate andinto the quenchant. The zone Z is a band of megasonic energy extendingacross the chamber. The substrate transport 28 pulls the substratethrough zone Z so as to expose the entire substrate to the zone Z. Thearea of the band is preferably selected such that when the substratepasses through the zone, up to 30% of the surface area of a face of thesubstrate is positioned within the band. Most preferably, as the centerof the substrate passes through the zone, only approximately 3-30% ofthe surface area of a face of the substrate is positioned within theband.

[0063] The substrate is raised and lowered through zone Z one or moretimes as needed for a thorough quench. The raising and lowering may beperformed at any desired speed, although a rate of approximately 25-300mm/sec has been found to be beneficial. As the substrate passes from theupper region 12 b into the bulk rinse fluid, particles entrained at thesubstrate surface are released at the gas/liquid interface and areflushed over the weir and out of the chamber. The expression “gas/liquidinterface” as used herein refers to the interface between air present inthe chamber (and/or gas or vapor introduced into the chamber) and fluidin the lower region 12 a of the chamber. Preferably the zone Z iscreated slightly below the gas/liquid interface.

[0064] It should be noted that the lower megasonic transducer may remainpowered on while the substrate is translated through the zone Z.

[0065] The quenching process may be enhanced by a stream of DI waterpreferably directed into upper region 12 b through fluid applicators 37.As the substrate transport 28 pulls the substrate through the chamber,the substrate passes through zone Z and through the stream of freshwater. During movement of the substrate upwardly past the fluid stream,the fluid stream applies a thin layer of fresh rinse fluid to theportion of the substrate at which the boundary layer was just thinned byzone Z. The substrate may be moved upwardly and downwardly through thezone Z and the fluid stream one or more times as needed for a thoroughquench.

[0066] The timing of energization of the transducers 32 a, 32 b may beselected depending on the goals of the process or the nature of thesubstrate surface (e.g. whether it is hydrophobic or hydrophilic). Insome instances it may be desirable to energize the transducers 32 a, 32b only during extraction of the substrate from lower region 12 a intoupper region 12 b, or only during insertion of the substrate into lowerregion 12 a, or during both extraction and insertion.

[0067] After quenching, DI water may continue to circulate through thechamber until such time as the chamber, end effectors and substrate havebeen thoroughly rinsed.

[0068] Cleaning

[0069] A substrate cleaning step may also be performed utilizing thefirst embodiment. If etching is performed, the cleaning step may occurbefore and/or after the etch process. Prior to cleaning, the chamber isdrained by moving the fluid manifold 18 away from the window 16. If thefluid handling configuration of FIG. 1C is used, the megasonics manifold22 is moved to the closed position covering the opening. During thecleaning process, a cleaning solution (for example, a solution of water,NH₂OH and H₂O₂ that is known in the industry as “SC1”) is introducedinto the chamber 10 via megasonics manifold 22 and caused to cascadeover weir 34. Alternatively, if a fluid handling configuration such asthat shown in FIG. 1D is used, the cleaning solution enters the manifold23 and chamber 10 via the appropriate one of the dedicated valves 33 c.

[0070] Megasonic transducers 32 a,b are energized during cleaning so asto impart megasonic energy into an adjacent region of the processfluid—and in doing so create zone Z (FIGS. 2A through 2C) of optimumperformance within the chamber. If necessary to prevent fine featuredamage, one of the transducers may by operated at low power or zeropower.

[0071] Throughout cleaning, the substrate transport 28 moves thesubstrate upwardly and downwardly one or more times (as required by thespecifics of the process) to move the entire substrate through the zoneZ of optimum performance. The substrate may be translated through thezone at any desired speed, although a rate of approximately 25-300mm/sec has been found beneficial.

[0072] As with the quenching process, the timing of energization of thetransducers 32 a, 32 b may be selected depending on the goals of theprocess. In some instances it may be desirable to energize thetransducers 32 a, 32 b only during extraction of the substrate fromlower region 12 a into upper region 12 b, or only during insertion ofthe substrate into lower region 12 a, or during both extraction andinsertion.

[0073] The zone Z is a band of megasonic energy extending across thechamber, preferably slightly below the gas/liquid interface. Thesubstrate transport 28 pulls the substrate through the band so as toexpose the entire substrate to the zone Z. The area of the band ispreferably selected such that when the substrate passes through thezone, up to 30% of the surface area of a face of the substrate ispositioned within the band. Most preferably, as the center of thesubstrate passes through the zone, only approximately 3-30% of thesurface area of a face of the substrate is positioned within the band.

[0074] Creation of zone Z is optimal for cleaning for a number ofreasons. First, cleaning efficiency is enhanced by minimizing thethickness of the boundary layer of fluid that attaches to the substratesurface—so that the cleaning solution can more effectively contact thesubstrate surface and so that reaction byproducts can desorb. Themegasonic energy from transducers 32 a, 32 b thin the boundary layer bycreating regional turbulence adjacent the substrate. Since transducers32 a, 32 b are directed towards the front and back surfaces of thesubstrate, this boundary layer thinning occurs on the front and backsurfaces. The megasonic energy further causes microcavitation within thefluid, i.e. formation of microbubbles that subsequently implode,releasing energy that dislodges particles from the substrate. Themegasonic turbulence keeps particles in the fluid suspended in the bulkand less likely to be drawn into contact with the substrate. Lastly,high velocity fluid flow through the chamber and over the weir movesparticles away from the zone and thus minimizes re-attachment. This highvelocity flow may be enhanced as discussed using a narrowed throatregion in the upper end of the chamber, or using an active mechanismsuch as a bellows-type device, to accelerate fluid flow through thezone.

[0075] Further optimization of cleaning at zone Z may be achieved byintroducing a gas such as nitrogen, oxygen, helium or argon into upperinterior region 12 b via gas inlet port 38. The gas diffuses into thevolume of cleaning solution that is near the surface of the cleaningsolution and increases the microcavitation effect of the megasonictransducers in the zone Z of optimal performance.

[0076] The lower megasonic transducer associated with manifold 22 (or,in the case of the FIG. 1D embodiment, a megasonic transducer associatedwith manifold 23 or separately positioned in the lower portion of thechamber) may be activated during the cleaning process, to as to createan acoustic streaming effect within the chamber, in which streams ofmicrobubbles are formed that keep liberated particles suspended in thebulk fluid until they are flushed over the weir 34, so as to minimizeparticle re-attachment to the substrate. It has been found to bedesirable, but not required, to operate the lower megasonic transducerwhile the upper megasonic transducers 32 are also activated and whilethe substrate is being translated through the zone Z.

[0077] It should be noted that while some minimal boundary layerthinning may be caused by activation of the lower transducer(s),boundary layer thinning is not the objective of activation of themegasonics associated with this transducer. Creating the zone Z in whichthe boundary layer is thinned as described above, rather than relyingupon acoustic streaming procedures for boundary layer thinning of theentire substrate surface, is advantageous in that by keeping theboundary layer relatively thicker outside the zone, the chance ofparticle reattachment is minimized.

[0078] To further minimize the chance of particle reattachment, aparticle gettering surface (not shown) may be positioned in the chambernear zone Z. During cleaning, a charge is induced on the getteringsurface such that particles liberated from the substrate surface aredrawn to the gettering surface and thus away from the substrate. Afterthe substrate has passed out of zone Z, the polarity of the getteringsurface is reversed, causing release of particles from the getteringsurface. These released particles are flushed out of the chamber 10 andinto the weir by the flowing cleaning fluid.

[0079] A charge may also be induced on the end effector 30 so as to drawparticles off of the substrate when the end effector is in contact withthe substrate. Later, the polarity of the end effector is reversed,causing particles gettered into the end effector to be released into theflowing cleaning fluid in the chamber and to be flushed into the weir.

[0080] The cleaning process will result in release of gases from thecleaning solution into the upper interior region 12 b, some of which maycontact exposed regions of the substrate and cause pitting at thesubstrate surface. To avoid such exposure, select vapors are introducedinto the upper chamber region 12 b via vapor inlet port 36. The vaporscondense on the substrate to form a protective film. If any released gasshould condense on the substrate, it will react with the protective filmrather than reacting with the silicon surface of the substrate. Forexample, an SC1 cleaning solution will cause off-gassing of ammonia intothe chamber. In this example, hydrogen peroxide vapor would beintroduced into the upper region 12 b to form a protective film on thesubstrate. Ammonia released by the cleaning solution will react with theprotective film rather than pitting the substrate surface.

[0081] After the substrate has been exposed to cleaning solution for therequired process time, the substrate is rinsed using a rinse solution.The rinse solution naturally will be dependent on the cleaning processbeing carried out. Following back end of the line (BEOL) cleaning, anisopropyl alcohol or dilute acid rinse may be carried out. After frontend cleaning process such as SC1 cleaning, a DI water rinse ispreferable. Rinsing may be-accomplished in various ways. For example,with the substrate preferably elevated above the cleaning solution inthe chamber, the cleaning solution may be suctioned back through themanifold 22 into a low pressure container 31 b in the manner describedin connection with the etch process. Next, rinse fluid is introducedinto the chamber 10 (via, for example, manifold 22 of FIG. 1C, manifold23 of FIG. 1D) and cascades over the weir 34.

[0082] The substrate is lowered into the rinse water and the waterrinses the cleaning solution from the chamber 10 and from the surface ofthe substrate. Alternatively, with the substrate remaining in thecleaning solution, rinse fluid may be introduced into the lower regionchamber, thereby flushing the cleaning solution from the chamber 10 intothe weir 34 as it rinses the chamber and substrate.

[0083] Megasonic energy from the side transducers 32 a, 32 b and/or thelower transducer is optionally directed into the rinse water chamber soas to enhance the rinse process. The substrate may be passed throughzone Z multiple times (again at a rate that may, but need not be, withinthe range of 25-300 mm/sec) as needed for thorough rinsing. A gas suchas nitrogen, oxygen, helium or argon may be introduced into upperinterior region 12 b via gas inlet port 38. The gas diffuses into thevolume of rinse fluid that is near the gas/liquid interface (i.e. theinterface between the upper surface of the rinse fluid and the gas orair above it) and surface of the rinse fluid and increases themicrocavitation effect of the megasonic transducers in zone Z.

[0084] The power state of the transducers is selected as appropriate forthe stage of the rinsing process and the surface state of the substrate.Preferably, both of the side transducers 32 a, 32 b and the lowertransducer are powered “on” during insertion of the substrate into therinse fluid. Depending upon the surface state of the substrate (e.g.whether it is hydrophilic or hydrophobic), the side transducers 32 a, 32b may be on or off during extraction of the substrate into the upperregion 12 b.

[0085] Reactive Gas Rinse

[0086] At some point during wet processing, the substrate may be exposedto a reactive gas (such as, for example, ozone, chlorine or ammonia) soas to interact with the substrate surface. Preferably, the reactive gasis dissolved in a rinse fluid and the substrate is exposed to the rinsefluid for an appropriate length of time.

[0087] The reactive gas rinse may be carried out with megasonic energybeing used to create a turbulent flow of the reactive gas rinse fluid.The turbulent flow thins the boundary layer of fluid attached to thesubstrate, so as to enhance reactive gas diffusion through the boundarylayer into contact with the substrate surface. Turbulence may be createdusing a megasonic transducer positioned in the bottom of the chamber asreactive gas rinse fluid flows into the chamber via one of the fluidmanifolds. Alternatively, reactive gas may be introduced, via nozzles 36or additional nozzles, into the upper interior 12 b of the chamber asrinse water flows into the chamber via one of the fluid manifolds. Thegas dissolves into the rinse water near the surface of the rinse water.The upper megasonic transducers 32 a, 32 b are energized to causeboundary layer thinning in zone Z, creating a zone of optimal absorptionof reactive species onto the substrate surface. The substrate istranslated through the zone Z one or more times as needed for thereactive gas to effectively treat the substrate surface.

[0088] Pre-Dry Rinse

[0089] In certain processes it may be desirable to perform a pre-drypassivating rinse using hydrofluoric acid (HF), hydrochloric acid (HCl)or de-gassed DI water.

[0090] In such processes, the lower portion 12 a of the chamber 10 isfilled with passivation fluid. The passivation fluid may be injectedinto a DI water stream entering fluid manifold 18 (using, for example,the fluid handling configuration shown in FIG. 1C), causing it to flowinto the chamber 10 with the DI water. Alternatively, the passivationfluid may flow directly into manifold 18 and into chamber, or, if thefluid handling configuration of FIG. 1D is used, the fluid may entermanifold 23 and chamber 10 via dedicated valve 33 b. In either case, thesolution cascading over weir 34 may be recirculated back into thechamber 10 throughout the pre-dry rinse process, such as by collectingit into a (preferably) temperature-controlled vessel and circulating itback to manifold 18 for re-introduction into the chamber 10.Alternatively, the pre-dry rinse process may be a “one-pass” process inwhich the overflowing fluid is directed to a drain for disposal. As athird alternative, the flow of fluid may be terminated once the lowerportion 12 a of the chamber has been filled.

[0091] Substrate S is engaged by end effector 30 and moved into thesolution by the substrate transport device 28. Substrate S is positionedin the lower portion 12 a of the chamber, i.e. at an elevation belowthat of the weir 34, so that the substrate is fully immersed in thepassivation solution. As with the reactive gas step, the upper megasonictransducers 32 a, 32 b may be energized to cause boundary layer thinningin zone Z, creating an optimal zone for contact between the passivatingrinse fluid and the substrate surface. The substrate is translatedthrough the zone Z one or more times as needed for the passivating rinsefluid to effectively passivate the substrate surface. The use ofmegasonic energy may also prevent particle deposition onto thesubstrate, which can often occur using low-pH passivation solutions suchas HF or HCl.

[0092] Drying

[0093] After the final treatment and rinse steps are carried out, thesubstrate is dried within the chamber. Drying may be performed in anumber of ways—three of which will be described below. Each of the threeexamples described utilize an IPA vapor preferably carried into thechamber by a nitrogen gas flow. In each example, the IPA vapor ispreferably generated in an IPA generation chamber remote from thechamber 10, using one of a variety of IPA generation procedures knownthose skilled in the art. For example, IPA vapor may be created withinthe IPA generation chamber by injecting a pre-measured quantity of IPAliquid onto a heated surface within the IPA generation chamber. The IPAis heated on the heated surface to a temperature preferably less thanthe boiling point of IPA (which is 82.4° C. at 1 atmosphere). Heatingthe IPA increases the rate at which IPA vapor is generated and thusexpedites the process, creating an IPA vapor cloud. When the IPA vaporis needed in the chamber 10, nitrogen gas is passed through an inletinto the IPA generation chamber, and carries the IPA vapor out of theIPA generation chamber via an outlet that is fluidly coupled to thevapor inlet port 36 in chamber 10.

[0094] The three examples of drying processes using the IPA vapor willnext be described. In one embodiment, the bulk water used for the finalrinse may be rapidly discharged from the chamber 10 by rapidlywithdrawing the fluid into a negative pressure container, or byperforming a “quick dump” by moving megasonics manifold 22 to the openedposition (or, if drying follows an HF last process and rinse, fluidmanifold 18 is moved from the closed to opened position). Then a vaporof isopropyl alcohol is introduced into the chamber 10 via vapor inletport 36. The IPA vapor passes into the lower portion 12 a of the chamberand condenses on the surface of the substrate where it reduces thesurface tension of the water attached to the substrate, and thus causesthe water to sheet off of the substrate surfaces. Any remaining liquiddroplets may be evaporated from the substrate surface using gas, such asheated nitrogen gas, introduced through gas inlet port 38. Gas inletport 38 may include a gas manifold having outlets that are angleddownwardly. The end effector 30 may be used to move the substrate pastthis manifold to accelerate evaporation of remaining PA/water film fromthe surface of the substrate.

[0095] In an alternative drying process, an atmosphere of IPA vapor maybe formed in the upper interior region 12 b by introducing the vapor viavapor inlet port 36. According to this embodiment, the substratetransport 28 lifts the substrate from the lower interior region 12 ainto the IPA atmosphere in the upper interior region 12 b, where the IPAvapor condenses on the surface of the substrate, causing the surfacetension of the water attached to the substrate to be reduced, and thuscausing the water to sheet from the substrate surface.

[0096] The megasonic transducers 32 a, 32 b may be energized as thesubstrate is pulled from the DI water so as to create turbulence in zoneZ to thin the boundary layer of fluid attached to the substrate. Withthe boundary thinned by zone Z, IPA can diffuse more quickly onto thesurface of the substrate, thus leading to faster drying with less IPAusage. Thus, the substrate may be withdrawn into the IPA atmosphererelatively quickly, i.e. preferably at a rate of 30 mm/sec or less, andmost preferably at a rate of between approximately 8 mm/sec-30 mm/sec.This is on the order of ten times faster than prior extraction dryingmethods, which utilize a slow withdrawal (e.g. 0.25 to 5 mm/sec) tofacilitate a surface-tension gradient between fluid attached to thesubstrate and the bulk rinse water.

[0097] Again, gas such as heated nitrogen may be introduced via manifold38 to evaporate any remaining IPA and/or water film, and the substratemay be translated past the manifold 38 to accelerate this evaporationprocess.

[0098] In a third alternative embodiment, slow extraction-type dryingmay be utilized. The substrate may thus be slowly drawn from the bulk DIwater into the IPA vapor. Using this embodiment, the IPA condenses onthe liquid meniscus extending between the substrate and the bulk liquid.This results in a concentration gradient of IPA in the meniscus, andresults in so-called Marangoni flow of liquid from the substratesurface. Gas such as heated nitrogen gas may be directed from manifold38 onto the substrate to remove some of the residual water and/or IPAdroplets and/or film. The substrate may be moved past gas manifold 38 toaccelerate this evaporation step.

[0099] In each of the above three embodiments, care should be taken tomaintain the static pressure within the chamber during the various stepsin the drying processes.

[0100] Second Embodiment—Structure

[0101]FIG. 3A shows a second embodiment 100 of a single substrateprocessing chamber utilizing principles of the present invention.

[0102] Second embodiment 100 generally includes a process chamber 102, acontainment vessel 104, an end effector 106, a rotational actuator 108and a vertical actuator 110.

[0103] Referring to FIG. 3A, process chamber 102 includes closely spacedchamber walls 111 defining a lower interior region 113 a and an upperinterior region 113 b. An overflow weir 114 is positioned in the lowerregion 113 a, slightly below upper region 113 b. Overflow weir 114includes a wall section 115 over which fluids cascade into the weir 114during certain processing steps. At the bottom of the chamber 102 is alower opening 135 (FIG. 3B), and at the top of the chamber is an upperopening 142 (FIG. 4).

[0104] A vapor/gas manifold 116 is provided for directing vapors/gasesinto upper region 113 b of the chamber. Manifold 116 (best shown in FIG.4) includes walls 120 on opposite sides of upper region 113 b. Vapor/gasports 122 a, 122 b extend through walls 120 and are fluidly coupled tovapor/gas conduits 124 a, 124 b. A plurality of orifices 126 a, 126 bextend from conduits 124 a, 124 b into the chamber 102. The orifices 126a, 126 b may be downwardly angled as shown. The angles are preferably(but are not required to be) within the range of 45°-80° relative to thenormal to walls 120. Each port 122 a, 122 b is coupled to plumbing thatdelivers process vapors/gases through the ports 122 a,b and into chamber102 via conduits 124 a, b and orifices 126 a, 126 b.

[0105] Referring to FIG. 5, manifold 116 additionally includes drainports 128 extending from overflow weirs 114. Drain ports 128 are fluidlycoupled to plumbing (not shown) that carries overflow fluids from weir114 and away from the chamber for recirculation or disposal.

[0106] Within containment vessel 104 is a fluid manifold 130, whichincludes an elongated conduit 132, and a plurality of openings 134extending from conduit 132 into the lower region of the chamber 102.Fluid ports 133 are coupled to conduit 132 and are fluidly coupled to anetwork of plumbing. This plumbing network selectively delivers aselection of different process chemistries through the fluid ports 133into manifold 130 and thus into the chamber 102. Manifold 130 ismoveable to an opened position as shown in FIG. 3B to permit fluid inthe chamber to be rapidly discharged through lower opening 135 into adrain (not shown). Automation 137 is provided for moving the fluidmanifold between the open and closed position.

[0107] An end effector of the type shown in FIG. 6 may be used foreither of the first or second embodiments. End effector 136 includes ablock 138 and a pair of gripping members 140 that engage a substrate Sbetween them by engaging opposite edges of the substrate as shown.Vertical actuator 110 (FIG. 3A) moves block 138 and gripping members 140between a withdrawn position in which the substrate S is fully removedfrom the chamber 102, and an advanced position in which the substrate Sis fully disposed within the lower region 113 a. When in the advancedposition, block 138 closes against opening 142 (FIG. 4) of chamber 102so as to contain gases and vapors and so as to prevent migration ofparticles into the chamber.

[0108] When the end effector is in the withdrawn position, rotationalactuator 108 (FIG. 3A) is configured to rotate the end effector to alateral orientation. This is particularly desirable for large substrates(e.g. 300 mm) that are customarily housed in a horizontal arrangement ina storage device or carrier. The end effector can be made to retrieveand deposit substrates directly from/to such a carrier, or from aseparate robotic end effector provided for unloading/loading substratesfrom/to the carrier. The vertical and horizontal actuators preferablyutilize conventional robotics of the type known to those of skill in theart, and these as well as other automated features (e.g. those relatingto measurement and injection of process fluids/vapors/gases arecontrolled by a conventional controller such as a PLC controller.

[0109]FIGS. 7A through 7E show an alternative end effector 106 a havingan engaging mechanism found particularly beneficial when used with thedescribed embodiments. An alternative chamber 102 a having a differentshape than the chamber 102 is also described, although various otherchamber shapes may be utilized with the end effector 106 a. As will beunderstood from the description that follows, the end effector 106 a hastwo positions relative to the substrate: a transport position in whichthe substrate is securely held by the end effector, and a processposition in which the end effector stabilizes the substrate whilepermitting process fluids to flow into contact with the substrate'ssurface.

[0110] Referring to FIG. 7A, the end effector 106 a includes a pair ofsupport members 150, each of which includes an upper support 152, lowersupport 154, upper transport slot 156 and lower transport slot 158.During transport of the substrate, upper and lower transport slots 156,158 receive the edge of the substrate S as shown in FIGS. 7A and 7B,thereby supporting the substrate as it is moved into/out of/within thechamber 102 a.

[0111] As illustrated in FIGS. 7B-7D, a bottom notch 160 is mountedwithin the chamber 102 a (for example, to a chamber wall 11 a as shown).As the substrate is lowered into the process position in the chamber,the bottom edge of the substrate contacts bottom notch 160. Continueddownward movement of the end effector 106 causes the substrate to edgeto slip out of the upper and lower transport slots 156, 158. Once thesubstrate has been fully lowered into the process position within thechamber (FIG. 7D), its weight is supported by the bottom notch 160 andsupport members 152, 154 function to stabilize the substrate in thisprocess position. Specifically, as illustrated in FIG. 7E, the substrateedge is disposed between a slot in support member 152, which restrictsforward/backward movement of the substrate but preferably does not gripthe substrate—thereby keeping the substrate stable while allowingprocess fluid to flow through the slot. Support member 154 (whichpreferably does not include a slot) extends towards the substrate edgeand restricts lateral movement of the substrate.

[0112] Because the chamber walls 111 a are closely spaced, the chamberwalls preferably include recessed sections 162 (FIGS. 7B-7D) whichprovide additional space for receiving end effector members 150.

[0113] Second Embodiment—Operation

[0114] As with the first embodiment, the second embodiment may be usedfor a variety of steps, including but not limited to wet etch, clean,rinse and drying operations either alone or in combination with oneanother or with other process steps. Operation of the second embodimentwill be described in the context of an etch, clean and drying process,with rinses being performed following etching and cleaning. However itshould be understood that various other combinations of processes mightbe performed without departing from the scope of the present invention.It should also be understood that various steps described in connectionwith the first embodiment may be practiced using the second embodiment,including the described methods for boundary layer thinning,megasonic-assisted quenching, cleaning, rinsing and/or drying, ozonepassivation, chemical injection and exhaustion. Moreover, the rates andother values given as examples in connection with the first embodimentmay also be applied to use of the second and third embodiments.

[0115] Operation of the second embodiment begins with fluid manifold 130in the closed position as shown in FIG. 5. DI water is directed intofluid ports 133, through manifold conduit 132 and into the chamber 102through openings 134. The DI water passes through the lower interiorregion 113 a and cascades over wall 115 into weir 114 and out drainports 128. At the same time, nitrogen gas flows slowly into theuppermost of the fill ports 122 a,b in the vapor/gas manifold, causingthe nitrogen gas to flow through the associated conduits 124 a, 124 band into the upper region 113 b of the chamber 102 via orifices 126 a,126 b. This low flow maintains a slight positive pressure within thechamber 102. Preferably, this nitrogen flow continues throughoutetching, cleaning, rinsing and drying.

[0116] Substrate W is engaged by end effector 106 and moved into thecascading DI water by the automation system. Substrate S is positionedin the lower interior 113 a of the chamber. Process fluids necessary forthe etching procedure (e.g. HF) are injected into the DI water beingdelivered to fluid ports 133 into manifold, and are thus passed into thechamber 102 via fluid manifold 130. At the end of the etch procedure,delivery of etch solution into the chamber 102 is terminated. The etchsolution may be exhausted from the chamber and rinsing may be carriedout preferably using one of the rinse procedures described above. Forexample, pure DI water may continue to flow into the chamber 102 toflush the etch solution from the chamber and to rinse the substrate,manifold, and chamber.

[0117] In an alternative etch procedure, the lower interior 113 a may befilled with etch solution, and then the substrate lowered into thestatic volume of etch solution. After the required dwell time, acascading rinse or other type of rinse is preferably carried out asdescribed above.

[0118] Once the substrate is thoroughly rinsed, a cleaning solution (forexample, a solution of water, NH₂OH and H₂O₂ that is known in theindustry as “SC1”) is introduced into the chamber 102 via manifold 130and caused to cascade over wall 115 into weir 114. After the substratehas been exposed to the cleaning solution for the desired period oftime, injection of the cleaning solution into the DI stream isterminated, and pure DI water flows into the chamber 102 to rinse thesubstrate.

[0119] After the final treatment and rinse steps are carried out, thesubstrate is dried within the chamber 102. Drying may be performed in anumber of ways—each of which preferably utilizes IPA vapor generated ina manner similar to that described above.

[0120] In one example of a drying process, the bulk water used for thefinal rinse may be rapidly discharged from the chamber 102 by movingfluid manifold 130 to the opened position (FIG. 3B). A vapor ofisopropyl alcohol is then introduced into the upper portion 113 b of thechamber by passing the IPA vapor through the vapor/gas inlet port 122a,b, into the corresponding conduit 124 a,b and thus into the chambervia openings 126 a,b. The IPA vapor flows into lower portion 113 a ofthe chamber, where it condenses on the surface of the substrate where itreduces the surface tension of the water attached to the substrate, andthus causes the water to sheet off of the substrate surfaces. Anyremaining liquid droplets may be evaporated from the substrate surfaceusing a gas (e.g. heated nitrogen gas) introduced through the vapor/gasinlet ports 126 a, b.

[0121] Alternatively, an atmosphere of IPA vapor may be formed in theupper interior region 113 b by introducing the vapor via gas/vaporopenings 126 a,b. According to this embodiment, the end effector 106lifts the substrate from the lower interior region 113 a into the IPAatmosphere in the upper interior region 113 b. Withdrawal of thesubstrate into the IPA atmosphere may occur quickly, i.e. approximately8 to 30 mm/sec. The IPA vapor condenses on the surface of the substrate,causing the surface tension of the water attached to the substrate to bereduced, and thus causing the water to sheet from the substrate surface.A third opening similar to openings 126 a,b may be provided just aboveoverflow weir 0.114 to allow a vacuum to be applied so as to accelerateevaporation of the IPA or PA/water mixture. Again, gas such as heatednitrogen may be introduced to dry remaining IPA and/or droplets/filmfrom the substrate.

[0122] As another alternative, the substrate may be slowly drawn fromthe bulk DI water into the IPA vapor. Using this embodiment, the IPAcondenses on the liquid meniscus extending between the substrate and thebulk liquid. This results in a concentration gradient of IPA in themeniscus, and results in so-called Marangoni flow of liquid from thesubstrate surface. Gas (e.g. heated nitrogen gas) may be used followingthe Marangoni process to remove any residual water droplets.

[0123] Third Embodiment—Structure

[0124] Referring to FIG. 8, a third embodiment 200 of a single substrateprocessing chamber includes a chamber 210 having a lower interior region212 a proportioned to receive a substrate S for processing, an upperinterior region 212 b, and an opening 214 in the upper interior region212 a.

[0125] A substrate transport device (not shown) is provided and includesan end effector configured to engage a substrate S, preferably in themanner shown in FIG. 6. The transport device is driven by conventionalautomation (not shown) to move the substrate S through opening 214 into,out of, and within the chamber 210 in an edgewise direction.

[0126] A lid 215 is provided for sealing opening 214. The lid 215 may beoperable with the automation that also drives the end effector, or withseparate automation.

[0127] A fluid handling system (not shown) is configured to carryvarious process fluids (e.g. etch fluids, cleaning fluids, rinse wateretc.) into the lower interior region 212 a of the chamber 210. The fluidhandling system may take a variety of forms, including those describedwith respect to FIGS. 1A-1D, and 5.

[0128] One or more megasonic transducers (not shown) are provided in thelower region 212 a of the chamber 210. The lower transducer may bemounted to the walls of the chamber 210 in a manner known in the art, orit may comprise a portion of a manifold assembly as described above.When the lower megasonic transducer directs megasonic energy into fluidin the chamber, it induces acoustic streaming within the fluid—i.e.streams of microbubbles that aid in removal of contaminants from thesubstrate by keeping particles in motion within the process fluid so asto avoid their reattachment to the substrate.

[0129] Vapor inlet ports, fluid applicators, and gas manifolds extendinto the upper interior region 212 b of the chamber 210. Each is fluidlycoupled to a system of conduits that deliver the appropriate fluids,vapors and gases to the ports as needed during processing.

[0130] An upper overflow weir 234 is positioned below the opening 214.Process fluid flowing through the chamber and past substrate S cascadesinto the weir 234 and into overflow conduits 235 for recirculation backinto the fluid handling system and re-introduction into the chamber, orinto drain 233. One more megasonic transducers 232 (one shown in FIG.8), which may include a single transducer or an array of multipletransducers, is positioned at an elevation below that of the weir 234,and is oriented to direct megasonic energy into an upper portion of thechamber 210.

[0131] The energy interacts with the substrate as the substrate is movedupwardly and downwardly though the chamber 210 by the end effector. Itis desirable to orient the transducer such that its energy beaminteracts with the substrate surface at or near the surface of theprocess fluid, e.g. at a level within the top 0-20% of the chamberregion lying below the elevation of upper weir 234. The transducers maybe configured to direct megasonic energy in a direction normal to thesubstrate surface or at an angle from normal. Preferably, energy isdirected at an angle of approximately 0-30 degrees from normal, and mostpreferably approximately 5-30 degrees from normal. The power andorientation of the transducer(s) may be adjustable in the mannerdescribed in connection with the first embodiment.

[0132] When energized, the transducer 232 creates a zone Z of optimalperformance within the process fluid in the chamber. As will bediscussed in greater detail below, energization of the zone enhancespost-etch quenching, cleaning, rinsing and drying processes throughregional boundary layer thinning and microcavitation.

[0133] A lower weir 240 is positioned beneath the elevation of thetransducer 232. Lower weir 240 optionally includes a door 242 having aclosed position, which prevents flow of fluid into the weir. When weir240 is in the closed position, fluid flowing into the chamber flows pasttransducer 232 and cascades over upper weir 234. When lower weir 240 isin the opened position, fluid flowing into the chamber cascades throughweir 234 and does not flow into contact with transducer 232. The lowerweir 240 is used to shunt away harsh chemicals (such as an etch solutionutilizing hydrofluoric acid) that can damage the megasonic transducer.Although some transducer materials such as sapphire or Teflon can resistthe harsh effects of such chemicals, those materials are very expensiveand will increase the overall cost of the chamber. Moreover, providing aseparate weir for harsh chemicals also helps to keep those chemicals outof conduits used to carry other solutions, such as the conduits 235 thatre-circulate cleaning and rinsing solutions, and thus minimizescross-contamination of fluids.

[0134] Third Embodiment—Operation

[0135] Use of the chamber 200 will be described in the context of anetch, clean and drying process, in which rinses are performed followingetching and cleaning. Naturally, various other combinations of these orother process steps may be performed without departing from the scope ofthe present invention.

[0136] Etching

[0137] An etch operation preferably begins with the lower portion 212 aof the chamber 210 filled with process fluids necessary for the etchingprocedure (for example hydrofluoric acid (HF), ammonium fluoride and HF,or buffered oxide). These fluids are introduced via the fluid handlingsystem that directs process fluids into the lower end of the chamber.

[0138] A substrate S is engaged by the end effector (such as endeffector 30 of FIG. 6) and is moved into the etch solution. Substrate Sis positioned in the lower portion 212 a of the chamber such that itsupper edge is below the elevation of lower weir 240. If provided, thedoor 242 of lower weir 240 is moved to the opened position. Etchsolution continues flowing into the chamber 210, and cascades into weir240.

[0139] The etch preferably includes boundary layer thinning to assistthe etch solution in reaching and thus reacting with the substances thatare to be removed from the substrate surface. Boundary layer thinningmay be accomplished by inducing turbulence in the flowing etch fluidusing disturbances formed into the sidewalls of the chamber. The inducedturbulence may be enhanced using relatively high fluid flow rates andtemperatures for the etch solution. Other mechanisms for inducingturbulence in the etch solution, including those described in connectionwith the first and second embodiments, may also be utilized.

[0140] Post-Etch Quench and Rinse

[0141] At the end of the etch procedure, flow of etch solution isterminated and a post-etch rinsing step may be carried out to removeetch solution from the substrate and chamber.

[0142] The post-etch rinse process preferably includes a quenchingprocess, which accelerates diffusion of the etch chemistry from thesurface of the substrate out of the boundary layer of fluid attached tothe substrate and into the surrounding bulk fluid. Quenching ispreferably initiated using a rapid removal (e.g. in preferably, but notlimited to, less than approximately 1.0 second), of etch solution fromthe lower end chamber 210, such as using sealed pressure chambers suchas the chambers 31 a described in connection with FIG. 1C. Quicklyremoving the bulk etch solution from the chamber minimizes etchvariations across the substrate surface by more sharply ending theexposure of the substrate to the bulk etch fluid. This process ispreferably enhanced by simultaneously withdrawing the substrate from thechamber lower portion 212 a into the upper portion 212 b using thesubstrate transport.

[0143] Next, the lower weir 240 is moved the closed position and thechamber 210 is rapidly filled with a quenchant such as Dl water. Sinceat this time the substrate is in the upper portion 212 b of the chamber,rapid filling can be performed without concern that the substrate willbe splashed—an occurrence which could lead to lack of uniformity acrossthe substrate's surface. As the chamber 210 begins to fill, themegasonic transducer in the chamber bottom is operated at low power.Once the lower portion 212 a of the chamber has been partially filled,the substrate is lowered into the quenchant. The turbulence created bythe megasonic energy facilitates boundary layer thinning that thusfacilitates diffusion of etch chemistry from the boundary layer into thebulk rinse water.

[0144] The megasonic power is increased as the volume of quenchant inthe chamber increases. Beginning at a lower power and increasing thepower as the chamber fills minimizes the chance of high power megasonicenergy causing splashing of quenchant onto the substrate, and alsominimizes the likelihood that residual etch solution on the substrateand in the tank would aggressively etch the bottom portion of thesubstrate immersed in the water.

[0145] The flow of DI water or other quenchant into the chamberpreferably continues even after the substrate is fully immersed. Becauselower weir 240 is closed, the fluid level rises above megasonictransducer 232 and cascades into upper weir 234. The upper megasonictransducer 232 is energized and imparts megasonic energy into anadjacent region of the DI water in zone Z (FIGS. 2A through 2C). In zoneZ, the turbulence created by the megasonic energy causes boundary layerthinning and thus facilitates gettering of the etch material away fromthe substrate and into the fresh quenchant. The substrate is pulledthrough zone Z and is raised and lowered through zone Z one or moretimes as needed for a thorough quench. As with prior embodiments, thearea of the band is preferably selected such that when the substratepasses through the zone, up to 30% of the surface area of a face of thesubstrate is positioned within the band. Most preferably, as the centerof the substrate passes through the zone preferably approximately 3-30%of the surface area of one face of the substrate is positioned withinthe band.

[0146] As the substrate is lowed from the upper region 212 b into thebulk rinse fluid, particles entrained at the substrate surface arereleased at the air/liquid interface and are flushed over the weir andout of the chamber 210.

[0147] The quenching process may be enhanced by a stream of DI waterpreferably directed into upper region 212 b through fluid applicators(such as applicators 37 described in connection with the firstembodiment) located in the upper region. As the substrate transportpulls the substrate through the chamber, the substrate passes throughzone Z and through the stream of fresh water. During movement of thesubstrate upwardly past the fluid stream, the fluid stream applies athin layer of fresh rinse fluid to the portion of the substrate at whichthe boundary layer was just thinned by zone Z. The substrate may bemoved upwardly and downwardly through the zone Z and the fluid streamone or more times as needed for a thorough quench.

[0148] As previously discussed, the timing of energization of thetransducers 232 may depend on the goals of the process or the nature ofthe substrate surface (e.g. whether it is hydrophobic or hydrophilic).In some instances it may be desirable to energize the transducers 232only during extraction of the substrate from lower region 212 a intoupper region 212 b, or only during insertion of the substrate into lowerregion 212 a, or during both extraction and insertion.

[0149] After quenching, DI water may continue to circulate through thechamber until such time as the chamber, end effectors and substrate havebeen thoroughly rinsed.

[0150] Cleaning

[0151] Prior to cleaning, the chamber is drained in using one of avariety of methods, including one of the methods described above. Duringthe cleaning process, a cleaning solution (e.g. an “SC1” solution or aback-end cleaning solution) is introduced into the chamber 210 using thefluid handling system. Lower weir 240 remains in closed position andthus allows the cleaning fluid to rise above transducer 232 and tocascade over upper weir 234.

[0152] Megasonic transducer 232 is energized during cleaning so as toimpart megasonic energy into zone Z. The substrate transport moves thesubstrate upwardly and downwardly one or more times in an edgewisedirection to move the entire substrate through the zone Z. As with thequenching process, the timing of energization of the transducers 232 maybe selected depending on the goals of the process.

[0153] The zone Z optimizes cleaning for a number of reasons. First,cleaning efficiency is enhanced by creating regional turbulence thatthins the boundary layer and thus allows the cleaning solution toeffectively contact the substrate surface. The megasonic energy furthercauses microcavitation within the fluid, i.e. formation of microbubblesthat subsequently implode, releasing energy that dislodges particlesfrom the substrate Microcavitation may be enhanced by introducing a gassuch as nitrogen, oxygen, helium or argon into upper interior region 212b via a gas inlet port, such that the gas diffuses into the volume ofcleaning solution that is near the surface of the cleaning solution.

[0154] Second, the megasonic turbulence also keeps particles in thefluid suspended in the bulk and less likely to be drawn into contactwith the substrate. Finally, high velocity fluid flow through thechamber and over the weir moves particles away from the zone and thusminimizes re-attachment.

[0155] A megasonic transducer in the lower region 212 b may be activatedduring the cleaning process, so as to create an acoustic streamingeffect within the chamber, keeping liberated particles suspended in thebulk fluid until they are flushed over the weir 234. This minimizes thechance of particle reattachment. To further minimize the chance ofparticle reattachment, a particle gettering surface (not shown) may bepositioned in the chamber near zone Z. During cleaning, a charge isinduced on the gettering surface such that particles liberated from thesubstrate surface are drawn to the gettering surface and thus away fromthe substrate. After the substrate has passed out of zone Z, thepolarity of the gettering surface is reversed, causing release ofparticles from the gettering surface. These released particles areflushed out of the chamber 10 and into the weir by the flowing cleaningfluid.

[0156] The cleaning process will result in release of gases from thecleaning solution into the upper interior region 212 b, some of whichmay contact exposed regions of the substrate and cause pitting at thesubstrate surface. To avoid such exposure, select vapors are introducedinto the upper region 212 b via a vapor inlet port so as to form aprotective film on the substrate. If reactive gases released from thecleaning solution condense on the substrate, they will react with theprotective film rather than reacting with the silicon surface of thesubstrate. For example, an SC1 cleaning solution will cause off-gassingof ammonia into the chamber. In this example, hydrogen peroxide vaporwould be introduced into the upper region 212 b to form a protectivefilm on the substrate. Ammonia released by the cleaning solution willreact with the protective film rather than pitting the substratesurface.

[0157] After the substrate has been exposed to cleaning solution for therequired process time, the substrate is rinsed using a rinse solution.The rinse solution naturally will be dependent on the cleaning processbeing carried out. Rinsing may be accomplished in various ways. In oneexample, the substrate is elevated above the cleaning solution in thechamber and the cleaning solution is withdrawn from the chamber using alow pressure container such as container 31 b described above. Rinsefluid is introduced into the chamber 210 and cascades over the upperweir 234.

[0158] The substrate is lowered into the rinse fluid and the fluidrinses the cleaning solution from the chamber 210 and from the surfaceof the substrate. Megasonic energy from the side transducers 232 and/ora lower transducer is optionally directed into the chamber so as toenhance the rinse process. The substrate may be passed through zone Zmultiple times as needed for thorough rinsing. A gas such as nitrogen,oxygen, helium or argon may be introduced into upper interior region 212b. The gas diffuses into the volume of rinse fluid that is near thegas/liquid interface (i.e. the interface between the upper surface ofthe rinse fluid and that gas above it) and increases the microcavitationeffect of the megasonic transducers in zone Z.

[0159] The power state of the transducers is selected as appropriate forthe stage of the rinsing process and the surface state of the substrate.Preferably, the side transducer 232 and the lower transducer are powered“on” during insertion of the substrate into the rinse fluid. Dependingupon the surface state of the substrate (e.g. whether it is hydrophilicor hydrophobic), the side transducer 232 may be on or off duringextraction of the substrate into the upper region 12 b.

[0160] Drying

[0161] The final rinse may be followed by any of a variety of dryingprocesses, including (but not limited to) those described in connectionwith the first and second embodiments.

[0162] Three embodiments utilizing principles of the present inventionhave been described. These embodiments are given only by way of exampleand are not intended to limit the scope of the claims—as the apparatusand method of the present invention may be configured and performed inmany ways besides those specifically described herein. Moreover,numerous features have been described in connection with each of thedescribed embodiments. It should be appreciated that the describedfeatures may be combined in various ways, and that features describedwith respect to one of the disclosed embodiments may likewise beincluded with the other embodiments without departing from the presentinvention.

claims 1-120. (CANCELED)
 121. A method of treating and drying asubstrate, the method comprising the steps of: (a) providing a chamberproportioned to process at least one substrate, the chamber including alower portion and an upper portion; (b) exposing at least one substrateto a process fluid in the lower portion of the chamber; (c) directingmegasonic energy into the process fluid, (d) forming an atmosphere ofdrying vapor in an upper region in the chamber; (e) during step (c),withdrawing the substrate from the process fluid in a lower region ofthe chamber into the upper region of the chamber.
 122. The method ofclaim 121, wherein step (c) forms a band of megasonic energy propagatingtowards a surface of the substrate, wherein the withdrawing step causesthe substrate to pass through the band, and wherein the megasonic energyinduces thinning of a boundary layer on the portion of the substratepassing through the band.
 123. The method of claim 122, wherein thewithdrawing step is performed at a rate of approximately 8-20 mm/sec.124. The method of claim 123, wherein the megasonic energy is propagatedin a direction normal to the substrate surface.
 125. The method of claim123, wherein the megasonic energy is propagated at an angle that is lessthan normal to the substrate surface.
 126. The method of claim 121,further including, after step (e), introducing a heated gas into thechamber to evaporate condensed drying vapor from the surface of thesubstrate.
 127. The method of claim 126, wherein the heated gas isintroduced through one or more inlets into the chamber, and wherein themethod further includes translating the substrate past the inlets toaccelerate evaporation.
 128. The method of claim 121, wherein step (b)includes exposing only one substrate to a process fluid in the lowerportion of the chamber.
 129. The method of claim 121, wherein theprocess fluid includes deionized water.
 130. The method of claim 121,wherein the drying vapor includes isopropyl alcohol vapor.
 131. Themethod of claim 121, wherein the atmosphere of drying vapor includesnitrogen gas.
 132. The method of claim 126, wherein the gas is nitrogengas.
 133. The method of claim 121, wherein the megasonic energy inducesthinning of a boundary layer on the substrate.
 134. An apparatus fortreating and drying a substrate, the apparatus comprising: a chamberproportioned to process at least one substrate, the chamber including alower portion and an upper portion; a source of a process fluid fluidlycoupled to the lower portion of the chamber; a source of drying vaporfluidly coupled to an upper portion of the chamber, to create anatmosphere of drying vapor in the upper portion; an end effector havinga substrate-receiving member moveable between the lower portion of thechamber and the upper portion of the chamber, said end effector operableto withdraw a substrate from process fluid in the lower portion into theatmosphere of drying vapor in the upper portion; and a megasonictransducer positioned to direct megasonic energy into process fluid inthe chamber.
 135. The apparatus of claim 134, wherein the transducer ispositioned to form a band of megasonic energy propagating towards asurface of the substrate, wherein the end effector is positioned to movethe substrate through the band, and wherein the megasonic energy inducesthinning of a boundary layer on the portion of the substrate passingthrough the band.
 136. The apparatus of claim 134, wherein the endeffector is configured to withdraw the substrate through the band at arate of approximately 8-20 mm/sec.
 137. The apparatus of claim 134,wherein the megasonic transducer is oriented to propagate energy in adirection normal to the substrate surface.
 138. The method of claim 134,wherein the megasonic transducer is oriented to propagate energy at anangle that is less than normal to the substrate surface.
 139. Theapparatus of claim 134, further including a source of heated gas fluidlycoupled to the chamber to volatilize condensed drying vapor from asurface of a substrate.
 140. The apparatus of claim 139, furtherincluding one or more inlets in the chamber for introduction of theheated gas into the chamber, and an end effector having asubstrate-receiving portion moveable to translate a substrate past theinlets to accelerate evaporation.
 141. The apparatus of claim 134,wherein the drying vapor includes isopropyl alcohol.
 142. The apparatusof claim 134, wherein the apparatus includes a system, the chamberforming a part of the system, and wherein the apparatus further includesmeans for exhausting drying vapor from the system.
 143. The apparatus ofclaim 134, wherein the process fluid includes deionized water.
 144. Theapparatus of claim 134, wherein the chamber is proportioned to processonly one substrate at a time.
 145. The apparatus of claim 134, whereinthe transducer is positioned such that megasonic energy induces thinningof a boundary layer on the substrate as the substrate is moved from theprocess fluid into the atmosphere of drying vapor